If you were using RVSiteBuilder to create/maintain your site, you'll need to wait until it's been re-installed into cPanel. There are a lot of loose ends from the migration being tied up right now, and setting up the site builder is one of them. (Many account holders are equally- or worse-affected by other issues, so while the site builder might be your number one priority, it may come in at a somewhat lower number in the big picture view.)
It likely won't be compatible -- RVSiteBuilder uses its own proprietary format (and if I recall correctly, that format is stored using Zend compression, which the server understands, so you don't need to have the sitebuilder available to use the site), so the site's content probably won't be accessible to any of the other tools that might be available. My advice is to avoid convenience features like site builders, since you're pretty much locked in. There are decent alternatives you can use locally, like KompoZer (free) or Adobe Dreamweaver (a long way from free) that will let you create/update a site in a way that compiles to standard files you can use anywhere (and you'll have a local copy if ever you need to recover an account or switch hosts), and there are alternatives like WordPress as well if you need something more interactive -- you can maintain a local copy of both the site and the database(s) and deploy them anywhere that uses PHP and MySQL (which is to say, almost everywhere).